Technical Note: Contrast free angiography of the pulmonary vasculature in live mice using a laboratory x‐ray source

Abstract

Purpose:In vivo imaging of the pulmonary vasculature in small animals is difficult yet highly desirable in order to allow study of the effects of a host of dynamic biological processes such as hypoxic pulmonary vasoconstriction. Here the authors present an approach for the quantification of changes in the vasculature.Methods:A contrast free angiography technique is validated in silico through the use of computer-generated images and in vivo through microcomputed tomography (μCT) of live mice conducted using a laboratory-based x-ray source. Subsequent image processing on μCT data allowed for the quantification of the caliber of pulmonary vasculature without the need for external contrast agents. These measures were validated by comparing with quantitative contrast microangiography in the same mice.Results:Quantification of arterial diameters from the method proposed in this study is validated against laboratory-based x-ray contrast microangiography. The authors find that there is a high degree of correlation (R = 0.91) between measures from microangiography and their contrast free method.Conclusions:A technique for quantification of murine pulmonary vasculature without the need for contrast is presented. As such, this technique could be applied for longitudinal studies of animals to study changes to vasculature without the risk of premature death in sensitive mouse models of disease. This approach may also be of value in the clinical setting.

Application of a novel in vivo imaging approach to measure pulmonary vascular responses in mice

“…Reconstructed pulmonary vascular trees from the noncontrast CT scans were obtained using the CFPA image analysis technique developed and previously reported by some of the authors of this study (Samarage et al. ; Dubsky et al. ).…”

“…The segmentation of the pulmonary vasculature was based on the contrast‐free pulmonary angiography (CFPA) technique by Samarage et al. (). This technique uses a Hessian‐based filter that uses multiple Gaussian scales to detect the probability of a tube‐like structure in the 3D image (Frangi et al.…”

“…A number of authors on this study used laboratory‐based 4DCT x‐ray imaging and postimage acquistion analysis (Samarage et al. ) to generate three‐dimensional, quantitative pulmonary vascular trees from scans acquired without intravenous contrast. We compared the measurements of vessel diameters obtained using this method to measurements obtained in the same animals via pulmonary angiography with intravenous contrast and found excellent correlation.…”

Will Airway Gene Therapy for Cystic Fibrosis Improve Lung Function? New Imaging Technologies Can Help Us Find Out

“…91,92 Unlike these methods, CFPA analysis can be done with prior CT scans and does not require contrast agents. CFPA has been validated through preclinical studies, 93,94 and is currently in the process of clinical validation. CFPA can be combined with XV analysis to further enhance the functional data, providing a contrastfree ventilation/perfusion (VQ) analysis.…”

Novel imaging approaches for small animal models of lung disease (2017 Grover Conference series)

“…Over 490 vessels were measured, with an excellent correlation (R 2 = 0.85) between diameter measurements obtained from the traditional angiography approach and the non-contrast reconstruction of the vascular tree. 74 We are now applying this non-contrast vascular reconstruction technique, termed “contrast-free pulmonary angiography,” to the analysis of vascular responses to acute lung injury and acute hypoxia. Other obvious applications include measuring vasculopathy—and responses to therapies—in mouse and rat models of PH.…”